Examinando por Autor "Carlos Riquelme"

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    Insights into the diversity and survival strategies of soil bacterial isolates from the Atacama Desert
    (2024) Alicyn Reverdy; Daniel Hathaway; Jessica Jha; Gabriel Michaels; Jeffrey Sullivan; Daniela Diaz McAdoo; Carlos Riquelme; Yunrong Chai; Veronica Godoy Carter
    The Atacama Desert, the driest, with the highest radiation, and one of the most ancient deserts in the world, is a hostile environment for life. We have a collection of 74 unique bacterial isolates after cultivation and confirmation by 16S rRNA gene sequencing. Pigmentation, biofilm formation, antimicrobial production against Escherichia coli MG1655 and Staphylococcus aureus HG003,and antibiotic resistance were assessed on these isolates. We found that approximately a third of the colonies produced pigments, 80% of isolates formed biofilms, many isolates produce growth inhibiting activities against E. coliand/orS. aureus, and many were resistant to antibiotics. The functional characterization of these isolates gives us insight into the adaptive bacterial strategies in harsh environments and enables us to learn about their possible use in agriculture,healthcare, or biotechnology.
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    Nitrification characteristics and microbial community changes during conversion of freshwater to seawater in down-flow hanging sponge reactor
    (2024) Takumi Akamine; Mami Nagai; Takahiro Watari; Hirotoshi Netsu; Nur Adlin; Penpicha Satanwat; Carlos Riquelme; Masashi Hatamoto; Takashi Yamaguchi
    In recirculating aquaculture systems (RAS), maintaining water quality in aquaculture tanks is a paramount factor for effective fish production. A down-flow hanging sponge (DHS) reactor, a trickling filter system used for water treatment of RAS that employs sponges to retain biomass, has high nitrification activity. However, nitrification in seawater RAS requires a long start-up time owing to the high salinity stress. Therefore, this study aimed to evaluate the nitrification characteristics and changes in the microbial community during the conversion of freshwater to seawater in a DHSreactor fed with ammonia-based artificial seawater. The total ammonia nitrogen concentration reached 1.0 mg-N⋅L 1 (initial concentration 10 mg-N⋅L 1) within 11 days of operation, and nitrate production was observed. The 16 S rRNA gene sequence of the DHS-retained sludge indicated that the detection rate of the ammonia-oxidizing archaeon Candidatus Nitrosocosmicus decreased from 23.9 % to 14.0 % and 25.8–17.6 % in the upper and lower parts of the DHS reactor, respectively, after the introduction of seawater. In contrast, the nitrite-oxidizing bacteria Nitrospira spp. increased from 0.1 % to 9.5 % and from 0.5 % to 10.5 %, respectively. The ammonia oxidation rates of 0.12 ±0.064 and 0.051 ±0.0043 mg-N⋅g-MLVSS 1⋅h 1 on the 37th day in the upper and bottom layers, respectively. Thus, nitrification in the DHS reactor performed well, even under high-salinity conditions with short operational days. This finding makes the transition from freshwater to saltwater fish in the RAS system simple and economical, and has the potential for early start-up of the RAS.
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    Ítem
    Rapid detection of enterobacteria in wastewater treated by microalgal consortia using loop-mediated isothermal amplification (LAMP)
    (2024) Henry Cameron; Jazmín Bazaes; Claudia Sepúlveda; Carlos Riquelme
    In the present study, nine Enterobacteriaceae species present in wastewater were isolated and identified, and loop-mediated isothermal amplification (LAMP) was developed for the detection of Enterobacteriaceae by designing primers based on the mcr-1, KPC, OXA-23, and VIM genes, which are recognized markers of antimicrobial resistance (AMR) transmission during microalgal bioremediation treatment. The developed assays successfully detected four strains positive for mcr-1 gene-asociated resistance (Acinetobacter baylyi, Klebsiella pneumoniae, Morganella morganii, and Serratia liquefaciens), three strains for KPC gene-associated resistance (Acinetobacter sp., Escherichia coli 15499, and Morganella morganii), seven strains for OXA-23 gene-associated resistance (Acinetobacter baylyi, Enterobacter hormaechi, Enterobacter cloacae, Escherichia coli 15922, Escherichia coli 51446, Morganella morganii, and Serratia liquefaciens), and three strains for resistance to the VIM gene-associated resistance (Acinetobacter baylyi, Acinetobacter sp., and Enterobacter hormaechi) from a single colony. A reduction in microbiological load of 93.6% was achieved at 15 colony-forming units (CFU) mL-1, utilizing EMB agar and LAMP values of 0.142 +/- 0.011 for the mcr-1 gene, 0.212 +/- 0.02 for the KPC gene, 0.233 +/- 0.006 for the OXA-23 gene, and 0.219 +/- 0.035 for the VIM gene. Furthermore, bioremediation efficiency values of 71.6% and 75% for total nitrogen and phosphorus, respectively, were observed at 72 h of treatment in open pond microalgal remediation systems (MRS). This study demonstrated that the LAMP technique is faster and more sensitive than traditional detection methods, such as CFU, for Enterobacteriaceae. Consequently, this method may be considered for the detection of microbiological quality indicators within the water treatment industry.
  • Miniatura
    Ítem
    Rapid detection of enterobacteria inwastewater treated by microalgal consortiausing loop-mediated isothermalamplification (LAMP)
    (2024) Henry Cameron; Jazmín Bazaes; Claudia Sepúlveda; Carlos Riquelme
    In the present study, nine Enterobacteriaceae species present in wastewater were isolated and identified, and loop-mediated isothermal amplification (LAMP) was developed for the detection of Enterobacteriaceae by designing primers based on themcr-1, KPC, OXA-23, and VIM genes, which are recognized markers of antimicrobial resistance (AMR) transmission during microalgal bioremediation treatment. The developed assays successfully detected four strains positive for mcr-1gene-asociated resistance (Acinetobacter baylyi,Klebsiella pneumoniae,Morganellamorganii, andSerratia liquefaciens), three strains for KPC gene-associated resistance(Acinetobacter sp.,Escherichia coli15499, and Morganella morganii), seven strains for OXA-23 gene-associated resistance (Acinetobacter baylyi,Enterobacterhormaechi,Enterobacter cloacae,Escherichia coli15922,Escherichia coli51446,Morganella morganii, and Serratia liquefaciens), and three strains for resistance to the VIM gene-associated resistance (Acinetobacter baylyi,Acinetobactersp., and Enterobacter hormaechi) from a single colony. A reduction in microbiological load of93.6% was achieved at 15 colony-forming units (CFU) mL-1, utilizing EMB agar andLAMP values of 0.142 ± 0.011 for the mcr-1 gene, 0.212 ± 0.02 for the KPC gene,0.233 ± 0.006 for the OXA-23 gene, and 0.219 ± 0.035 for the VIM gene.Furthermore, bioremediation efficiency values of 71.6% and 75% for total nitrogen and phosphorus, respectively, were observed at 72 h of treatment in open pond microalgal remediation systems (MRS). This study demonstrated that the LAMP technique is faster and more sensitive than traditional detection methods, such as CFU, for Enterobacteriaceae. Consequently, this method may be considered for the detection of microbiological quality indicators within the water treatment industry
  • Miniatura
    Ítem
    Whole-genome sequencing of a Janthinobacterium sp. isolatedfrom the Patagonian Desert
    (2024) Nicole T. Cavanaugh; Girish Kumar; Alicyn Reverdy Pearson; Julia Colbert; Carlos Riquelme; André O. Hudson; Yunrong Chai; Veronica Godoy Carter
    Janthinobacterium is a genus of Gram-negative environmental bacteria that survive extreme conditions by forming biofilms and producing pigments. Janthinobacterium sp. LS2A, an extremophile isolated from soil in the Chilean Patagonia, contains seven known biosynthetic gene clusters, including the purple pigment violacein, which may aid in its survival in harsh environments.